Operating mechanism for doubleacting automatic brake slack adjusters



April 14, 1942. B. H. BROWALL 2,219,653

OPERATING MECHANISM FOR DOUBLE-ACTING AUTOMATIC BRAKE S LACK ADJUSTERS Filed April 19, 1940 2 Sheets-Sheet 1 April 1942- B. H. BROWALL 2,279,653

OPERATING MECHANISM FOR DOUBLE-ACTING AUTOMATIC BRAKE SLACK ADJUSTERS 2 Sheets-Sheet 2 Filed April 19, 1940 Patented Apr. 14, 1942 OPERATING MECHANISM FOR DOUBLE- ACTING AUTOMATIC BRAKE SLACKAD- JUSTERS Application April 19, 1940, Serial No. 330,619 In Germany April 19, 1939 4 Claims.

This invention relates to slack adjusters for brakes and more particularly to double-acting automatic slack adjusters of the type comprising a brake rod and a member axially slidable onsaid brake rod in both directions and adapted to be moved in relation to said brake rod in one direction at application and in the other direction at release of the brake. In automatic slack adjusters of this type, disclosed in the U. S. Patent No. 2,035,228 to Gallusser and in my U. S. Patent No. 2,225,001, granted December 17, 1940, and defined as double-acting for the reason that they are capable not only of reducing the slack when too large but also of increasing the slack when too small, the said axially slidable member on the brake rod performs the double function of coacting with a relatively movable part of the brake rod for moving said part in the slack reducing direction in relation to the main part of the brake rod at release of the brake, and of controlling a brake power transmitting coupling between the two relatively movable brake rod parts for limiting their relative movement in the slack increasing direction at application of the brake. For

operating the slidable member-on the brake rod which the slidable member on thebrake rod is moved in one direction by an operating rod at application of the brake. In the known construction of this kind, in which the said spring moves the slidable member on the brake rod back into normal position at release of the brake, the operation of the brake is materially disturbed by the said spring because of the fact that the brake power is counteracted by the power of the said spring and that this must be rather strong, namely strong enough for overcoming, without yielding, the resistance against movement of the brake rigging, even if the latter should be heavy to move. In other proposed constructions of the operating mechanism use is made of a rotatable operating guide plate for effecting the movement of the slidable member on the brake rod in both directions. Constructions of this kind are very bulky, and further they cannot easily be made such as to render the slack adjuster selflocking against unintentional slack increasing movement due to shocks or the like, for instance when switching the cars, at released brake.

The chief object of the present invention is to provide an operating mechanism for slack adjusters of the type set forth, which is of a simple and neat construction and which is reliable in its action. A further object of the invention is to against slack increasing movement at-released brake.

With all these and other'objects in view which will occur in the course of the following specification the invention consists in the construction,

arrangement and combination of parts hereinafter fully set forth and claimed.

The invention is illustrated by way of examples in the accompanying drawings in which:

' Fig. 1 is a plan View, partly in section, of parts of an automatic slack adjuster and one form of operating mechanism therefor embodying the invention, the parts being shown ina position ofx the application movement of the brake.

Fig, 2- is a view similar to Fig. 1 but with the parts in a position of the brake application movement beyond the distance corresponding to the normal value of theslack. r

Fig. 3 is a plan view, partly in section, of parts of an automatic slack adjuster and another formof operating mechanism therefor embodying the invention, the parts being shown in a position corresponding to released brake.

Fig. 4 is a section substantially on the line IV"-L IV in Fig. 3;

Fig. 5 is a section substantially on the line VV Y in Fig. 3. I Referring to the drawings, l denotes a live brake lever and 2 a brake rod linked to said brake lever at the free end thereof. 3 denotes an operating rod, and this operating rod and the brake rod 2 are relatively movable in one direclever coupled to the live brake lever, or the ope'ratin rod 3 may be connected to a fixed point if there is no dead brake lever coupled to the live brake lever. 4 denotes a member which is slidable on the brake rod 2 andforms part of a doukale-acting automatic slack adjuster of the The member 4 is 'constructed as a casing for a compressed spring 5, I

type herein referred to.

against the action of which the member 4 is axially displaced on the brake rod 2 by the operating rod 3 at application of the brake.

As is well known in the art the member 4 performs the double function of coacting with a relatively movable part of the brake rod for moving said part in the slack reducing direction in relation to the main part of the brake rod 2 at release of the brake, and of controlling a brake power transmitting coupling between the two relatively movable brake rod parts for limiting their relative movement in the slack increasing direction at the free end of this 'armB is a guiding roller 1 co-- acting with a guiding surface 8: on the operating rod 3 for guiding the latter. at its. movement in relation to the brake rod 2-. At the side opposite to the guiding surface 8 the operating rod 3 is provided with a guiding surface 9 which, as well,

as the guiding surface 8, extends in a direction parallel to the direction of movement of the-op-- erating rod 3 in relation to the brake rod 2.

cess' Hl'formed in the operating -rod 3. 0n. the

side facing the operating rod 3 the brake rod 2 is provided with alongitudinally extending ledge.

H. A latch l2, preferably T-shaped,. is: pivoted at the end of its middle legto the'arm 6 on the member 4 and is provided with'rollers i3- and I4 at the ends of its other legs. Atiits free end the operating rod 3 is provided with an oblique surface l5- joining the guiding surface 9 at the outer end thereof One endof the-ledge -l acts as an abutment for coaction with the roller 13011 the latch I 2.

The operation of the operating: mechanism now described is as follows. With the latch I 2 in the position shown in Fig. 1, which it'takcs during the normal slack. consuming part of the application. stroke; of. the brake, thelatch t2 supports itself with its' roller M against the: guiding surfaces and isthereby held withthe roller. l3 in? engagement with the abutment H a. formed by the end of the ledge H on. the main. brake rod 2. Thus, in this position the latch I2 locks theslidable member 4 to the brake rod 2,. so that the member 4 must partake in the movement of the main brake rod 2 in relationto. the operating rod 3: When thebrake, at application thereof,. has

travelled a distancecorr'espcndingr to the normal valuerof-the slack; the roller. I4 reaches and enters-the recess iii, whereby the roller I3 is no longer heldinengagement with-the abutment I la but is allowed to moveialong the ledge II at thecontinued relative movement. of the brake rod 2 and the operating rod 3 as shown in Fig. 2. By the-coaction of the roller IS with the: ledge II the latch IE from now is held with the roller. [4 en.- gaged in the recess ll], thereby locking the memberr4 to the operating. rod 3 and thus preventing themember 4 from partaking in the. movement of thebrakerod 2 in relation to the operating. rod 3. Atthis movement in the brake application direction the member 4 is axially displaced on the brake rod 2 against the actionof the compressed' spring 5. The member. 4 remains locked to the operating rod 3 until during the following. release of the brake the roller l3 again reaches the abut At" its inner end the guiding surface 9 ends in a rement i la, whereby the roller I4 is no longer held in the recess I 0 but is allowed to move out of the recess is and along the guiding surface 9.

In slack adjusters of the type herein referred to it is well known that the slack adjuster is locked against slack increasing movement as a result of a'mcvement of the member 4 on the main brake rod 2 against the action of the spring 5 and due to the fact that the hereinbefore mentioned brakestress transmitting coupling between the two relatively movable brake rod parts of the slack adjuster is rendered active by such a move ment of the member 4 and, when active, prevents relative movement of the said two brake rod parts in the slack increasing direction. It is also known to render the slack adjuster self-locking against unintentional slack increasing movement at released brake by affording freedom to the member 4 to be moved on the brake rod 2 against the actionof the spring 5 by the action of such a stress-int the brake rod as may be caused by a jolt or shock, for instance when switching the. cars, andwould result in a'slack increasing'movement should the slack adjuster not-be able tolock itself thereagainst. 'In the form of the invention illustrated in Figs. 1 and 2 the requisite freedom of movement of the member for rendering the slack adjuster selflocking againstslack increasing movementv at released brake is obtainedsimply due to the inclined surface IS on the operating. rod 3. Towards the end of the brake release movement the roller I4 comes on the. inclined surface 5, and due to this, atfully released-brake, the latch I2 is no longer. held with its roller l3 in engagementwiththe abutment Ha but isfree to movewith-the roller [3 out-of engagementwith the abutment Ma and along the ledge H, thus great strength of the spring-5. is required so that;

thespring 5 can be made sufficiently weak for not disturbing the braking operation to any appreciable degree.

Theform of the. invention-illustrated in Figs.

1 and 2 is of a remarkably simple construction.

but. does not completely safeguardv against unintentional slack. increasing movement of theslack.

adjuster under the. action of: jolts and shocks: at-

released. brake. The fact is. that it. may happen: that the brake, at the release thereof aftera braking. operation... is prevented, for; instance:- by

a handbrake. that has not been fully released, from. reaching: thefully released position: and:.is-

stopped in. a position: before the roller l4 has against unintentional. sla-ck' increasing movement due to shocks and the like.

The form of the invention. illustrated" in Figs;

3. and. 4 isconstructed with a view to enable. the

slack adjuster to lock itself against slack increas ing movement at released brake irrespectiveof: the position in which the release movement of the brake might have. been stopped. The form: of Figs. 3 and 4 is constructed also with a. viewto provide anenclosing casing for the parts operatively connecting the slidable member 4 to the operating'rod 3. In the form of Figs. 3 and 4 the arm 6 in the form of Figs. 1 and 2 is substituted by a casing I6 which is fixed to the member 4 and surrounds both the brake rod 2 and the end portion IQ of the operating rod 3. The said end portion l9 extends through and is guided in two openings I1 and IS in the casing l6. As in the form of Figs. 1 and 2 a recess I is provided in the operating rod 3, namely in the end portion L9. The latter supports itself laterally against the roller 1 which is journalled in the casing IS. The latch l2 carrying the rollers l3 and M is not pivoted directly to the casing IE but to the free end of a swingable arm 2!! journalled on a shaft 2| in the casing IS. The arm 2|] comprises two parallel legs united at both ends by two journals 22 and 23 receiving the shaft 2| and the pivot pin |2a of the latch l2, respectively. The journal 23 at the free end of the arm is provided with a projection 24, and a spring supports itself at one end against the free end of this projection 24 and at the other end against a shoe 25 which slidably supports itself against one side of the end portion IQ of the operating rod 3. The spring 25 presses the shoe 23 against the operating rod portion l9 and tends to rotate the arm 20 in the anticlockwise direction as viewed in Fig. 3. The latch l2 comprises two parallel legs interconnected by means of the pivot pin I21; and shafts l2 and I2" for the rollers l3 and M. An abutment arm 21 is pivoted in two opposing journal cups 28 screwed into the casing IS. The abutment arm 2! is provided with a recess 29 for the spring 25 and with two pins 33 engaging the H-shaped shoe 26 between its legs, the arrangement being such, that the abutment arm 21 is swingable between two positions by movement of the shoe 2'6 in either direction by the operating rod 3. In one of these postions of the abutment arm 21 the free end thereof is in the path of the journal 23 and prevents the arm 2|] from being swung in the clockwise direction as viewed in Fig. 3. In the other position the abutment arm 21 supports itself against the portion I9 of the operat-- ing rod 3 and permits the arm 20 to be swung in the said clockwise direction. The operating rod 3 is provided with an abutment flange 3| which at application of the brake, when the brake has travelled the distance corresponding to the normal value of the slack, abuts the casing l3 and,

at the continued brake application movement displaces the casing I6 together with the member 4 against the action of the spring 5. The end wall of the casing i6 is provided with an aperture 32 for the ledge II, and the brake rod 2 is provided with a projection 33 for closing this aperture in the normal position of the member 4.

The operation of the now described mechanism according to Figs. 3 and 4 is as follows. The parts are shown in the position corresponding to released brake. Supposing that a stress arises in the brake rod, due for instance to a switching shock or the like, the abutment arm 2'! permits the arm 20 to turn about its shaft 2| in the clockwise direction as viewed in Fig. 3. This means that the latch l2 does not lock the casing l6 and the member 4 to the brake rod 2 but permits movement of the member 4 on the brake rod 2 against the action of the spring 5, in spite of the roller l3 being engaged with the abutment Ha. This freedom of movement of 'themember 4 in relation to the brake rod' 2 enables the slack adjuster to lock itself against any slack increasing movement that otherwise might be caused by an arising stress in the brake rod. As soon as at a beginning application movement of the brake the operating rod 3 begins to move to the left, as viewed in Fig. 3 in relationto thebrake rod 2, the spring pressed shoe 26, due to its frictional contact with the brake rod portion l9, will partake in this movement of the operating rod 3, and the abutment arm 2'1, due to the engagement of its pins 30 with the shoe 26, will be swung in the clockwise direction, as viewed in Fig. 3, into the position in. which it coacts with the journal 23 for preventing the arm 20 from being swung tothe right aboutthe shaft 2|. As a result thereof the latch I2 during application movement of the brake, until the roller l4 reaches and can enter the recess ID in the operating rod portion l9, acts to lock the casing l6 and the member 4 to the brake rod 2. In the moment the roller I4 enters the recess III for locking the member 4 to the operating rod 3, the flange 3| abuts the casing 16, and at the continued brake application movement the operating rod 3 displaces the casing I6 and the member 4 in relation to the brake rod 2 against the action of the spring 5. As soon as the brake is moved in the release direction the operating rod 3 is moved to the right, as viewed in Fig. 3, in relation to the brake rod 2, whereby the shoe 26 is also moved to the right and swings the abutment arm 21 into the position shown in Fig. 3. Thus, the abutment arm 21 is swung into this last mentioned position at the beginning of any release movement of the brake and remains in this position during the whole release movement and until it is again swung into the other position at the beginning of a new brake application movement Consequently, at released brake, irrespective of the position in which the release movement might have been stopped, the member 4 is always free to be moved against the action of the spring 5 for enabling the slack adjuster to lock itself against such slack increasing movement as otherwise might take place under the action of switching shocks and the like.

What I claim and desire to secure by Letters Patent is:

1. In an operating mechanism for doubleacting automatic brake slack adjusters of the type comprising a brake rod and a member slidable axially in both directions on said brake rod, a member for operating said slidable member by relative movement of said operating member and said brake rod in one direction at application and in the other direction at release of the brake, and a member mounted on said slidable member and movable under the control of the relative movement between said operating member and said brake rod into either of two positions, for locking said slidable member to either said brake rod or said operating member.

2. An operating mechanism as claimed in claim 1, in which said locking member is in the form of a latch swingably mounted on said axially slidable member andadapted to be held by said operating member in locking engagement with said brake rod until at application of the brake the latter has travelled a distance corresponding to a normal value of the brake slack.

3. An operating mechanism as claimed in claim 1, in which guiding means are provided on said operating member and said brake rod for moying and holding said locking member in locking engagement with said brake rodxat application of the brake until the latter has travelled a distance corresponding to a normal value of the brake slack, and in looking engagement with said operating member at movement of the brake beyond said distance.

4. In an operating mechanism for doubleacting automatic brake slack adjusters of the type comprising a brake rod and a member slidable axially in both directions on said brake rod, a member for operating said axially slidable member by relative movement of said operating member and said brake rod in one direction at application and in the other direction at release of the brake, a latch movable into either of two positions for engagement with said brake rod and said operating member, respectively, guiding means on said operating member and said brake rod for moving and holding said latch in the first of said positions at application of the brake until the latter :has travelled a distance corresponding to a normal value of the brake slack, and in the other of said positionsat movement of the brake beyond said distance, a member carrying said latch and movably mounted on said axially slidable member so as to per mit axial movement of said latch along with said brake rod in relation to said axially slidable member upon occurrence of switching shocks an abutment mounted on said axially slidable member and shiftable in and out of an active position for preventing, when in active position, axial movement of'said axially slidable member on said brake rod inrelation to said latch, and means operable by a beginning relative'movement of said operating member and said brake rod in the brake application direction and in the brake release direction for shifting said abutment into and out of said active position, respectively.

BERT HENRY BROWALL. 

